1. Field of the Invention
The present invention relates in general to data storage devices, and it particularly relates to methods for mass producing a disk drive head with a numerical aperture (NA) catadioptric focusing device, using wafer processing techniques. The present invention further relates to a catadioptric focusing device with high numerical aperture (NA) for use in data storage systems such as optical and magneto-optical (MO) disk drives.
2. Description of Related Art
In a MO storage system, a thin film read/write head includes an optical assembly for directing and focusing an optical beam, such as a laser beam, and an electro-magnetic coil that generates a magnetic field for defining the magnetic domains in a spinning data storage medium or disk. The head is secured to a rotary actuator magnet and a voice coil assembly by a suspension and an actuator arm positioned over a surface of the disk. In operation, a lift force is generated by the aerodynamic interaction between the head and the disk. The lift force is opposed by equal and opposite spring forces applied by the suspension such that a predetermined flying height is maintained over a full radial stroke of the rotary actuator assembly above the surface of the disk.
A significant concern with the design of the MO head is to increase the recording or areal density of the disk. One attempt to achieve objective is to reduce the spot size of the light beam on the disk. The diameter of the spot size is generally proportional to the numerical aperture (NA) of an objective lens forming part of the optical assembly, and inversely proportional to the wavelength of the optical beam. As a result, the objective lens is selected to have a large NA. However, objective lenses with a large NA increase the spot aberration on the disk, thus adversely affecting the MO head performance.
Another concern related to the manufacture of MO heads is the extreme difficulty and high costs associated with the mass production of these heads, particularly where optical and electro-magnetic components are assembled to a slider body, and aligned for optimal performance.